Also test traversal.Get linkloader configuration.

This doesn't add much in the way of coverage, since it's internally
quickly convergenced with what the Focus tests cover, but in testing,
explicitness is good.

traversal/focus_test.go

@@ -180,3 +180,30 @@ func TestFocusWithLinkLoading(t *testing.T) {
 		Wish(t, err, ShouldEqual, nil)
 	})
 }
+
+func TestGetWithLinkLoading(t *testing.T) {
+	t.Run("link traversal with no configured loader should fail", func(t *testing.T) {
+		t.Run("terminal link should fail", func(t *testing.T) {
+			_, err := traversal.Get(middleMapNode, ipld.ParsePath("nested/alink"))
+			Wish(t, err.Error(), ShouldEqual, `error traversing node at "nested/alink": could not load link "`+leafAlphaLnk.String()+`": no LinkTargetNodePrototypeChooser configured`)
+		})
+		t.Run("mid-path link should fail", func(t *testing.T) {
+			_, err := traversal.Get(rootNode, ipld.ParsePath("linkedMap/nested/nonlink"))
+			Wish(t, err.Error(), ShouldEqual, `error traversing node at "linkedMap": could not load link "`+middleMapNodeLnk.String()+`": no LinkTargetNodePrototypeChooser configured`)
+		})
+	})
+	t.Run("link traversal with loader should work", func(t *testing.T) {
+		n, err := traversal.Progress{
+			Cfg: &traversal.Config{
+				LinkLoader: func(lnk ipld.Link, _ ipld.LinkContext) (io.Reader, error) {
+					return bytes.NewBuffer(storage[lnk]), nil
+				},
+				LinkTargetNodePrototypeChooser: func(_ ipld.Link, _ ipld.LinkContext) (ipld.NodePrototype, error) {
+					return basicnode.Prototype__Any{}, nil
+				},
+			},
+		}.Get(rootNode, ipld.ParsePath("linkedMap/nested/nonlink"))
+		Wish(t, err, ShouldEqual, nil)
+		Wish(t, n, ShouldEqual, basicnode.NewString("zoo"))
+	})
+}